A vane rotary compressor is used for an air conditioner and the like and compresses a fluid such as refrigerant so as to supply the compressed fluid to the outside.
FIG. 1 is a cross-sectional view schematically illustrating a conventional vane rotary compressor disclosed in Japanese Unexamined Patent Application Publication No. 2009-07937 (Patent Document 1). FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1.
As shown in FIGS. 1 and 2, the conventional vane rotary compressor includes a hollow cylinder 1, a rotor 2 installed within the cylinder 1, a vane 4 slidably inserted into a vane slot 3 of the rotor 2, a rotary shaft 5 formed integrally with the rotor 2 to be axially rotatably supported, and a front cover 6 and a rear cover 7 which close both ends of the cylinder 1 to define a compression chamber 8.
In this case, the compression chamber 8 communicates with an inlet 9 and an outlet 10, the outlet 10 is provided with a discharge valve 11, and the rear cover 7 is formed with a high pressure passage 12 so as to communicate with a high pressure chamber in a rear housing 13 mounted on a rear surface of the rear cover 7.
Meanwhile, the rear housing 13 is formed, at a lower portion thereof, with an oil room 13a, and oil contained in compressed refrigerant, which is compressed in the compression chamber 8 and discharged to the high pressure chamber, is separated by an oil separator (not shown) in the rear housing 13 to be stored in the oil room 13a. 
In this case, oil stored in the oil room 13a is supplied to the rotor 2 through an oil supply passage 18 formed on one side of the rear cover 7, and the rear housing 13 is formed, at an upper portion thereof, with a discharge port 14 through which compressed refrigerant is discharged to an air conditioning system.
A space divided by the vane slot 3, the front cover 6, and the rear cover 7 constitutes a back pressure chamber 20. The vane 4 slides along the vane slot 3 by the pressure of the back pressure chamber 20 and a front end portion of the vane 4 is supported by an inner peripheral surface of the cylinder 1.
In addition, the rear cover 7 is formed with a circular arc-shaped oil groove 19 through which the back pressure chamber 20 at the rear end of the vane 4 communicates with the oil supply passage 18.
The conventional vane rotary compressor configured as described above operates as follows.
First, when the rotor 2 receives power from a drive source such as an engine and rotates along with the rotary shaft 5, low pressure refrigerant is introduced into the compression chamber 8 through the inlet 9 and compressed while the volume of the compression chamber 8 is reduced along with rotation of the rotor 2.
Then, the compressed refrigerant is discharged to the high pressure passage 12 through the outlet 10, introduced into the rear housing 13, and supplied to the air conditioning system through the discharge port 14.
In this case, oil separated by the oil separator in the upper portion of the rear housing 13 is dropped and stored into the oil room 13a. The stored oil is supplied to the back pressure chamber 20 at the rear end of the vane 4 via the oil supply passage 18 and the oil groove 19 so as to lubricate the vane 4.
Meanwhile, the vane 4 is pushed out along the vane slot 3 by the pressure of oil supplied to the back pressure chamber 20 and the front end portion of the vane 4 is pressed against the inner peripheral surface of the cylinder 1, thereby dividing a space between the inner peripheral surface of the cylinder 1 and an outer peripheral surface of the rotor 2 into a plurality of compression chambers 8.
In a case in which the vane 4 is configured in a linear form as the above-mentioned conventional art, high pressure oil must be continually supplied to the back pressure chamber 20 in order for the front end portion of the vane 4 to be maintained in a state of being pressed against the inner peripheral surface of the cylinder 1. Accordingly, this results in an increase in consumption power (HP) of the compressor.
In addition, excessive force is concentrated on a point at which the front end portion of the vane 4 comes into contact with the inner peripheral surface of the cylinder 1, depending upon pushing the vane 4 by the high pressure of oil in the back pressure chamber 20. Therefore, this causes an increase in torque of the rotary shaft of the compressor.
In addition, in a case in which refrigerant discharge pressure is not properly formed in the initial stage of driving the compressor, since the pressure of separated oil is low and thus force to push the vane 4 from the back pressure chamber 20 is insufficient, chattering noise is generated while the front end portion of the vane 4 discontinuously rubs against the inner peripheral surface of the cylinder 1.
Moreover, a distance by which the conventional linear vane emerges from the vane slot is limited. Accordingly, the inner peripheral surface of the cylinder has been used in a state of being restricted to a simple circle (one stroke/one rotation) as described above or an oval (two strokes/one rotation) as shown in FIG. 3.
FIG. 3 is a cross-sectional view schematically illustrating a two-stroke vane rotary compressor disclosed in Japanese Unexamined Patent Application Publication No. 2010-31759 (Patent Document 2). Here, compression and intake strokes are performed twice during one rotation of a rotor.
When a rotor 2′ comes into contact with an inner peripheral surface of a cylinder 1′ at two points in the oval cylinder 1′ having a hollow, a compression stroke is short, thereby affecting consumption power (HP), reducing a coefficient of performance (COP) of the compressor, and directly affecting fuel efficiency of a vehicle.
In addition, similarly as described in an example of one stroke compressor of FIGS. 1 and 2, there are problems in that chattering noise is generated due to a strike of a vane 4′ in the initial stage of driving the compressor, excessive force is concentrated on a point at which a front end portion of the vane 4′ comes into contact with the inner peripheral surface of the cylinder 1′ to thereby increase torque of a rotary shaft 5′, and high pressure oil must be continually supplied to a back pressure chamber 20′ to thereby increase consumption power (HP) of the compressor.